Widespread use of urea was delayed in part due to its greater potential for nitrogen (N) loss via ammonia volatilization in calcareous soils. Elemental sulfur (S⁰) can be applied to acidify calcareous soils which reduce N loss via ammonia volatilization and increases fertilizer nitrogen use efficiency. The present study was sought to examine the effect of S⁰ combined with or without N on total dry matter (TDM), N uptake,  percentages of  N derived from fertilizer (%Ndff), Total fertilizer N recovery (%FNR),  fertilizer N use efficiency (%FNUE) and fertilizer N loss (%FN loss) by corn plants grown in calcareous soils. Elemental S at rates of 0, 1, 5 and 10 t ha^-1 were tested combined with or without labeled N-15 (10% atom enrichment) urea fertilizer at rates of 0 and 0.34 t ha^-1 in greenhouse pot experiment using two soils differed in CaCO₃ content (Al Zaid soil, 38 % and Al Semaih soil, 69%). Addition of S⁰ at the rate of 5 t.ha¹ in Al Zaid and Al Semaih soil combined with N fertilizer recorded improve in TDM, total N uptake, %Ndff, %FNR and  %FNUE, and reduction in %NF loss. Collectively, the results indicate that S⁰ fertilization is required to improve FNUE and thereby maintaining a sufficient availability of N, reduction of N loss and better growth of corn in sandy calcareous soils.